This is a known error which has been fixed and is included in Mosaic RR23.2 release which is officially out now.
To upgrade to this version please raise a case after following the instructions on the knowledge article titled Upgrade Requests.
How the error is caused
When a person has a Fairer Charging element (for example), they are charged by the hours that have actually been delivered. These are otherwise known as 'actuals'.
These actuals can be entered manually but are more commonly loaded through an interface, such as CM2000/E-invoice/Abacus etc. When the interface runs it will load the actuals data into a table called DELIVERED_ACTUALS. This table has a column ID that serves as the unique index or primary key.
The actuals do not really have an impact until a payment cycle of the type 'einvoice' is ran that covers the period of which that the actual that was entered for.
When this happens, the actual is turned into a commitment and payment that is associated with an invoice for that payment cycle.
At that point, the actual then is moved from DELIVERED_ACTUALS to DELIVERED_ACTUALS_APPLIED that also has an ID column. Where the reports come into play is that there is a finance Mosaic datamart table called DM_FIN_DELIVERED_ACTUALS that also has its own primary key called ACTUAL_ID.
This combines the actuals from both tables into one. The ACTUAL_ID is made up for the ID from the source table and the element_detail_id.
The issue is that there is a person 1234566 for example that has actuals for different dates that share the same ID in both tables and those actuals also happen to be for the same element_detail_id.
The error occurs as the populate script tries to insert both with the same ACTUAL_ID which is not allowed.
So therefore, the delivered_actuals_applied is using the same id as the delivered_actuals id for the primary key and this causes the constraint error.
The upgrade to Mosaic RR 23.2 will resolve this issue.